1. Technical Field
The disclosure relates to a microscope focusing mechanism included in a microscope for illuminating a specimen with illumination light and receiving reflected or transmitted light from the specimen to observe the specimen.
2. Related Art
In the fields of medicine, biology, and the like, microscopes for illuminating a specimen for observation are used to observe cells or the like. Furthermore, in the field of industry, microscopes are used for various purposes, such as management of quality of metallographic structures, research and development of new materials, or examination of electronic devices or magnetic heads. As the observation of a specimen by the microscope, a monitor observation is known in addition to a visual observation. In the monitor observation, an image of a specimen is captured by using an imaging element such as a CCD or CMOS image sensor and the captured image is displayed on a monitor for observation.
A conventional microscope includes, as disclosed in Japanese Laid-open Patent Publication No. 9-120030 for example, a microscope frame that serves as a base of the microscope and that includes an optical system in the interior thereof. The microscope frame also includes, for example, a stage for placing a specimen, a revolver for replaceably holding a plurality of objective lenses with different magnifications with respect to the specimen, a focusing mechanism that supports the stage, that is movable in a vertical direction along an optical axis of an objective lens, and that adjusts a focus of the objective lens, and an eyepiece for observing an observation image formed by light emitted by the specimen. A lamp house is appropriately attached to the microscope frame to emit illumination light for illuminating a specimen on the stage. Another focusing mechanism may be provided for supporting the revolver in a vertically movable manner, instead of supporting the stage in a vertically movable manner.
The focusing mechanism is disposed on the microscope frame and moves along a guide extending in a specified direction. The focusing mechanism usually needs to have a higher rigidity in order to enable stable focusing operations and to obtain stable observation images. Therefore, a material such as steel or iron is used for a guide of the microscope frame and a guide member of the focusing mechanism. Meanwhile, a material such as aluminum is used for parts other than the guide and the guide member in the entire microscope including the focusing mechanism (a moving unit) in order to reduce weight. Thermal expansion coefficients of steel and iron are smaller than that of aluminum.